SU1621139A1 - Tracking a-d converter of low-level signals - Google Patents

Abstract

The invention relates to computing and measurement technology and can be used to digitize low level signals. The invention improves the accuracy of conversion and expands the scope of application due to the fact that a device containing a modulator, an AC signal amplifier, a multivibrator, two AND elements, a reversible counter, a digital-analog converter, a divider, a Schmidt trigger, two pulse shapers, an HE element . The active element (amplifier in the input circuit) is excluded from the device circuit and a passive feedback circuit element is introduced. Execution of the control circuit of the reversible counter in a corresponding way allows to eliminate the appearance of cut-off pulses at the input of the reversible counter. If the sampling frequency is not limited by the application of the device. 1 Il.

Description

The invention relates to the field of computing and measurement technology and can be used to digitize (parallel and reversible number-pulse code) low-level signals, such as signals from thermoelectric converters.

The aim of the invention is to improve the accuracy of converting low level signals and expanding the field of application of the device.

The drawing shows the functional diagram of the device

The next low-level ADC signal contains a modulator 1, a variable signal amplifier 2, a mulyvibrator 3, a reversible counter 4, a DAC 5, elements 6, 7, Schmidt trigger 8, drivers 9, 10

pulses, the element is NOT 11 and the divider is 12 voltages.

The convertible analog signal X (t) of a low level is fed to the first input of the modulator 1. The second input of the same modulator receives a compensating feedback signal XK (t) from the output of the voltage divider 12. The control input of the modulator 1 receives a modulating signal of a rectangular shape from the output of the multivibrator 3.

AC voltage from the output of the modulator 1 is fed through the AC amplifier 2 to the Schmidt trigger input 8 If the difference between the converted signal X (t) and the compensating signal XK (t) modulo uiat E0 quantization, the level of the alternating signal fed to the trigger input 8 Schmidt, exceeds it by |

U

horn V0 triggered. If the converted signal X (t) is greater than the compensating signal XK (t) (Undercompensation mode), then a square signal / 2 in phase with the modulating signal Vi will be generated at the output of Schmidt trigger 8, and if the converted signal X (t) is less than the compensating signal XK (t) (Overcompensation mode), then at the output of the trigger 8 a square signal / a is formed in antiphase with the modulating signal VL

On negative fronts (decays) of the V2 signal, the shaper 9 generates Va pulses, the duration of which is equal to 1/4 of the period of the modulating signal, and on the negative fronts (decays) of the Uz signals, the shaper 10 generates V4 pulses of standard duration. Logical functions are implemented by logical elements AND 6.7 and element 11.

K + - V4 A Vi; (1)

K V4 L Vi. (2)

As a result, in the Undercompensation mode, only code pulses K will be generated at the output of the element 6, which are fed to the input of the reversible counter 4, and in the Recompensation mode, only coaxial pulses K will be produced at the output of the element 7, which will be fed into the subtraction input inversely about the counter 4. The contents of the counter 4 will change, causing a corresponding change in the analog signal at the output of the DAC 5, and hence a change in the compensating signal Xk (t.) at the output of the voltage divider 12, Once the compensating signal XK (t) becomes equal to the converted signal X (t) with an accuracy of Eo, the formation of the variable signal at the output of Schmidt trigger 8 stops, and therefore the formation of code pulses K or K causing the change in the content of the reversible counter 4 will also stop This thereby ensures that the analog signal X (t) is low converted into

the digital form, in the process of which the first and second outputs of the device (the outputs of the elements And 6,7) form a reversible number pulse code

a sequence of code pulses K and K, formed at elementary positive and negative increments of the signal X (t), and at the third output of the device (the information output of the reverse

counter 4) a parallel binary code is formed that is proportional to the current value of the signal X (t).

Claims (1)

Invention Formula A low-level analog-to-digital signal converter that contains a modulator, the first information input of which is the converter input, the output is connected to the amplifier input a variable signal, and a control input with a multivibrator output, a reversible counter and a digital-to-analog converter, the inputs of which are connected to the corresponding outputs of a reversible counter and are the first output bus, the two AND elements, the outputs of which are connected to the inputs of the addition and subtraction of the reversible counter, and are respectively the second and third output tires, and the first the inputs are combined, characterized in that, in order to increase the accuracy of conversion and expansion of the field of application, a Schmidt trigger is introduced, two pulse shapers, the element NOT and voltage divider, whose input is connected to the output of a digital-to-analog converter, and the output to the second information input of the modulator, the output of the multivibrator is connected to the second input of the first element And, through the element NE to the second input of the second element And, the input of Schmidt trigger is connected to the output of the amplifier AC signal, and the output through two series-connected pulse driver is connected to the first input of the first element I. one